Difference between Standard & Separated Combustion type unit heaters
Unlike standard heaters, which use surrounding indoor air for combustion purposes, separated combustion heaters draw 100% of their combustion air from outdoors, through a separate pipe outlet in the unit. This design allows to protect the units’ burner when indoor air is dusty, dirty or humid (i.e. in greenhouses & nurseries, woodworking & stone cutting shops, etc.) and ensures that it has an uninterrupted supply of fresh air.
Modine’s separated combustion series includes HDS (Hot Dawg – for smaller residential and light commercial uses), PTS (for larger commercial and industrial uses) and PTC (high-efficiency condensing series for a wide range of applications).
Modine gas series for residential and light commercial uses
HD (Hot Dawg) series are the most popular small-size unit heaters in the USA, designed for garages, workshops and other applications. They are compact, versatile and powerful enough to be used as a primary heat source.
HDS (Hot Dawg Separated Combustion) series are a variation of the HD series with separated combustion design.
PTC series (models PTC55 through PTC110) includes high-efficiency (93%+) gas condensing unit heaters with separated combustion design. PTC heaters are the most energy efficient in the industry and can be vented using PVC & PolyPropylene (PP) pipe.
Modine gas series for commercial and industrial uses
PDP series heaters are the most popular choice due to their competitive pricing and simplistic, yet rugged design.
PTP series heaters incorporate a stainless steel heat exchanger (instead of aluminized steel used in other models) and are designed to last. They also feature a lower profile than PDP, but also come at a premium price.
PTS series heaters feature separated combustion design and low profile.
PTC series (Effinity models PTC135 and above) combine the best energy efficiency in the industry with a separated combustion design and low-profile construction.
Sizing and selecting a gas unit heater
As with all other heating equipment, unit heaters are primarily sized based on heat loss calculations, which factor in total square footage, ceiling height, insulation thickness, doors/windows, outdoor & desired indoor temperatures and many others. A comprehensive set of sizing literature can be found in any Modine unit heater’s listing on our website under the "Literature" tab.
Frequently Asked Questions
Q: Are these heaters propeller or blower type?
A: All the Modine gas units we sell are propeller type by default.
Q: What kind of vent do these units have?
A: All heaters have a power-exhaust vent (category III).
Q: What’s the max elevation?
A: Max elevation for Modine gas units is 2,000ft. Higher elevations require a high-altitude kit and will have ratings reduced by 4% for every 1,000ft.
Q: How to convert a NG heater to LP?
A: We offer NG to LP conversion kits for most models listed. Look in the product description for the part# of the kit.
Q: What kind of vent pipe must be used?
A: With the exception of PTC (condensing) series, which use PVC or PP (PolyPropylene) vent pipe, all others use standard chimney pipe. Vent pipe size is indicated in the product description under "Technical Specifications".
Q: Can these heaters be vented vertically or horizontally?
A: Modine gas unit heaters are power-vented, allowing for both vertical (through the roof) and horizontal (through a side wall) venting. Maximum vent pipe run varies by model and can be found in the individual product’s description.
Q: How a unit heater is secured to the wall/ceiling?
A: Mounting options vary by model. Smaller units (such as Hot Dawgs) come with L-shaped wall mounting brackets. Bigger commercial models are suspended to the ceiling using threaded rods and struts.
Q: What’s the warranty?
A: Standard Modine warranty for gas-fired units is 10 years for the heat exchanger (both heat exchangers in PTC series) and 2 years for parts.
